Human disease is frequently caused by pathogenic microorganisms representing the major categories of bacteria, viruses and fungi. The movement of an infectious particle from a host or infected individual to a susceptible new victim can occur by various mechanisms, including breathing of aerosolized fluids from the host, contact with surfaces contaminated by the host and host bodily fluids, or by transfer on the hands of the victim or third party from the host or from contaminated surfaces to the victim. The particular transfer mechanism depends on the organism as well as the particular setting. In hospitals and other clinical environments transfer on the hands of caregivers is considered a potentially important mechanism for organisms such as Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species (collectively known as ESKAPE pathogens) and Clostridium difficile. Additionally, multi-drug resistant organisms (MDROs), defined as microorganisms, predominantly bacteria, that are resistant to one or more classes of antimicrobial agents, have special clinical significance because of their acquired resistance. MDROs include but are not limited to Methicillin Resistant S. aureus (MRSA), Carbapenem Resistant Enterobacteriaceae (CRE), Multidrug-resistant A. baumannii (MDR-Ab), and Vancomycin-Resistant Enterococcus (VRE). The number of viable organisms and the site of contact required to start an infection in a new host depend on the infectivity of the organisms as well as the immune capacity of the new prospective host. Individuals with compromised or weak immune function, such as hospital patients, are typically more likely to become hosts for new infections. Hospital-acquired infections have become a significant problem for the health-care industry. The severity of this problem is likely to continue to increase as additional pathogenic organisms with antibiotic resistance arise.
Some microorganisms, such as norovirus, an intestinal pathogen, are a significant concern in the cruise ship industry and in assisted care/nursing home environments, where propagation can be rapid within a close-knit community. The illnesses caused can be life-threatening. The food preparation industry, for example, large-scale poultry packaging facilities, are periodically linked to outbreaks of antibiotic-resistant Salmonella enterica, causing numerous deaths. The role of hand contact in the spreading and transmission of the norovirus and salmonella organisms in these settings is likely to be significant.
The importance of good hand hygiene in clinical and food-preparation environments is well established, typically promoted in terms of hand washing or use of topical alcohol-containing gels. The conventional approaches, however, have certain limitations. Hand washing can remove contaminating superficial organisms without causing significant harm to the indigenous organisms found in the skin of healthy individuals. To be effective, hand-washing should take on the order of 30 seconds. However, this amount of time is prohibitive in fast-paced, high-stress critical care settings, and does not allow additional time for hand drying. Availability of sinks can also limit the use of this approach. Although the dispensing, application, and drying of an alcohol gel on the hands can be accomplished significantly faster than hand washing and drying, these steps also require a relatively long time—approximately 10-15 seconds.
Accordingly, there is a need for improved techniques and devices for sanitizing surfaces and hands in health care, home, and other settings.